1. Field of the Invention
This invention relates to skis used for snowmobiles and similar vehicles. More particularly, the invention relates to wear rods used on the snow-engaging surfaces of such skis to better control the steering behaviour of the vehicles.
2. Description of the Prior Art
Traditional wear rods consist of a round rod secured to the underside of the ski. Such rods perform two functions, namely they improve steering (particularly turning) and they provide protection for the ski base. The steering bias in such systems is uncontrollable. The length of the wear rod in front of the turning centre of the ski is greater than that which is behind. This allows self-energizing behavior or wander.
The only way a traditional wear rod can increase its turning ability is to extend further to the rear of the ski or to have a larger diameter. The lengthening of the rod far from the turning centre increases turning effort because of the leverage. If a larger rod is used, then steering effort again increases, as does the self-energizing problem.
One attempt to overcome these problems currently being marketed uses a separate flat carrier with an added round conventional rod in a shortened form. This has the obvious problem of inadequate turning ability. It is also difficult in this system to provide different options of round rod length with existing bolt patterns.
All round rods have problems of penetration into hard snow as the rods become worn because the contact width increases. It then requires more weight to penetrate properly. Snowmobiles are very sensitive to this problem and handling suffers considerably.